Video surveillance systems have wide application and can be used in a number of settings such as residential, commercial, governmental and industrial. Typically, one or more video cameras are strategically positioned in a protected or secure area, and used to capture images of people and other objects that come within the range of the cameras. Video surveillance systems can transmit surveillance information via wire-based and wireless technology, and across the Internet.
In addition to real-time monitoring by security personnel, many surveillance systems record and store surveillance footage to video tape or other medium for future reference and analysis. With the advent of digital storage, it is now possible to store video footage to a wide variety of digital storage devices, such as computer hard drives, optical disks and Digital Video Disks (DVDs).
In those systems that record video footage, all footage produced by a surveillance camera is typically stored in its entirety. The digital files generated by a video camera are very large and require a great deal of storage space. In addition, in order for a surveillance system to fully monitor an area, multiple cameras are generally required. As the number of cameras in a surveillance system increases, the amount of video data that is to be stored also increases.
In order to accommodate these storage requirements, many current surveillance system architectures make use of video archives that roll over after a certain timeframe. For example, a system may include a set of video tapes or computer disks that can store two months worth of continuous surveillance data. For two months, surveillance data is sequentially written to the set of tapes or disks until the set is full. At this point, the set of tapes or disks is re-used, starting with the first tape or disk that contains the oldest data. Any new video surveillance data is then stored on the first tape or disk in the set, overwriting the old surveillance data. Obviously, older surveillance video data, which may still have value, is lost in a system that performs rollover storage.
Alternatively, some systems back up or archive all video data wholesale to archival media once the data has become “stale.” That is, all data captured by the surveillance system is archived after a set period of time passes after the data is captured. In these systems, once data has been archived, it is no longer readily available to a user of the system. The archival media must be identified and loaded in order to view or obtain information about a particular event caught by surveillance video. Typically in these systems, all data is archived, and any data that is archived remains on the archival media permanently.
Although this method allows data to be stored for a long period of time, there is no practical way to identify, extract or peruse archived surveillance data. In order to view archived surveillance data of an event, a user must know exactly where in the voluminous surveillance data archive that the video containing the event resides. Sometimes, a user may be able to locate a section of the archived surveillance data to search for the video data of interest if the user knows some information about the timeframe and/or video camera in which the video was taken. However, even if a section of archived surveillance data can be identified, the user must still review that entire section of archived data in order to find the relevant video data. In many cases, this can be a complex and time consuming task, as many archival disks or other media may need to be identified, brought out of storage, loaded into the system and reviewed by a user before the video data of interest can be found.
The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.